The present invention relates to the general field of axial type rotary transformers used for transferring electrical power by electromagnetic induction between two elements.
An axial type rotary transformer is typically made up of two elements of circular shape that are radially superposed, namely an inner core having one or more outer annular grooves receiving toroidal coils, and an outer core mounted coaxially around the inner core and having one or more inner annular grooves facing the outer grooves of the inner core and receiving toroidal coils. These two elements of circular shape are mounted coaxially so that one of the elements can rotate relative to the other about a common longitudinal axis.
Existing solutions for fabricating such an axial type rotary transformer consist in making the inner and outer cores from a sintered ferrite material or else, for transformers of small sizes, by machining high-resistivity cast iron. For the inner core, the toroidal coils can then be built up by winding them directly in its outer grooves. As for the outer core, the toroidal coils are usually received in the inner grooves by being deformed.
Nevertheless, such an architecture for a rotary transformer raises a certain number of problems. In particular, when the toroidal coils are of large section, it is not always possible to deform them to enable them to be received in the inner grooves of the outer core, which means that it then becomes necessary to build up the outer core around those coils. Furthermore, the materials used (sintered ferrite or cast iron) are fragile and cannot always withstand the severe vibratory environments to which they can possibly be subjected, particularly in the field of aviation.